NO WAY...accidental deaths like Dent's are not exceptions to Batman's rule.

As for Ra's Al Ghul, he wasn't killed by Batman. He may have ended up in a deadly situation, but Batman didn't actually, physically kill him. Dent, however, was TACKLED OVER A BUILDING by Batman, and fell to his death. Batman could have gone about saving the boy differently, but no.

Ironic how Dent & Rachel died in the same place (250 52nd Street).
Also ironic how Bruce Wayne/Batman lost 2 people central to his crimefighting abilities in Rachel & Dent, and ALMOST lost a 3rd in Gordon.

Of course, this is ALL ASSUMING that Dent & Ra's Al Ghul are actually dead.

Maybe, perhaps. Of course no one but him (or Nolan) knows his situation at the time. He was just shot (separated plates leaves him vulnerable to knives and gunfire) and he had to do something suddenly at the right moment in order to save the boy, whom Harvey might've had a gun pointed to his head. Might've been the only thing he could do at a time, but there was no intention to kill. It was almost like self-defense, but this is just another way of looking at it. It's a debatable subject.